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The researchers discovered the material can act as a microphone, by capturing the vibrations from sound, or mechanical energy, and converting it to electrical energy.

It also works as a loudspeaker, by operating the opposite way: converting electrical energy to mechanical energy.

To demonstrate the microphone effect, the researchers developed a FENG security patch that uses voice recognition to access a computer, which was successful in protecting an individual's computer from outside users.

It is made up of a silicone wafer, which is fabricated with several layers silver, polyimide and polypropylene ferroelectret. Ions are added so that each layer in the device contains charged particles. Electrical energy is created when the device is compressed by human motion, or mechanical energy

Dr Sepulveda said: 'The device is so sensitive to the vibrations that it catches the frequency components of your voice.'

To demonstrate the loudspeaker effect, the FENG fabric was embedded into a Michigan State University flag.

Music was piped from an iPad through an amplifier and into the flag, which then reproduced the sound flawlessly.

Dr Sepulveda said: 'The flag itself became the loudspeaker.

'So we could use it in the future by taking traditional speakers, which are big, bulky and use a lot of power, and replacing them with this very flexible, thin, small device.'

Imagine a day when someone could pull a lightweight loudspeaker out of their pocket, slap it against the wall and transmit their speech to a roomful of people, Dr Sepulveda said.

Dr Nelson Sepulveda (pictured right) and Dr Wei Li (pictured left), who created the device, are pictured holding it in front of the WSU flag used to demonstrate its use as a loudspeaker

He added: 'Or imagine a newspaper where the sheets are microphones and loudspeakers.

'You could essentially have a voice-activated newspaper that talks back to you.'

Dr Wei Li, lead author of the study, added other potential applications of the FENG include noise-cancelling sheeting and a health-monitoring wristband that is voice-protected.

Dr Li said: 'Many people are focusing on the sight and touch aspects of flexible electronics, but we're also focusing on the speaking and listening aspects of the technology.'